Autophagic and phytochemical aspects of color changes in white petals of snapdragon flower during development and senescence.

Color change in petals is a clever strategy to attract more pollinators and one of the attractive features of edible flowers for consumers. Several physiological, phytochemical, and ultrastructural factors are involved in this process. However, this phenomenon is well underexplored in white petals. In this study, we investigated the color changes of the white petals of the snapdragon (Antirrhinum majus 'Legend White') flower from different aspects during development and senescence. In the ultrastructural analysis, both epidermal and mesophyll cells were examined. During flower development, plastid transition and autophagy processes led to the fading of the green color of young petals and the reduction of starch content, chlorophyll, and carotenoids. The piecemeal chlorophagy was observed in the degradation of starch granules. Leucoplasts were converted into autophagosome-like structures and then disappeared. The presence of these structures was evidence of the transformation of the plastid to the vacuole. As the green color faded, phytochemical compounds were synthesized. With partial flower opening and progression of senescence, pH and phenolic compounds were responsible for color changes. The highest amount of phenolic compound was observed after the flower opening stages. However, Phenolic colored compounds or total anthocyanins became colorless under the influence of low pH. The decrease in starch content caused an increase in the lightness parameter, and the petal color changed to pale yellow.

Antioxidant Compounds of Potato Breeding Genotypes and Commercial Cultivars with Yellow, Light Yellow, and White Flesh in Iran.

Potatoes are a staple food with high antioxidant properties that can positively affect population health. The beneficial effects of potatoes have been attributed to tuber quality. However, the tuber quality related researches at genetic levels are very few. Sexual hybridization is a powerful strategy for producing new and valuable genotypes with high quality. In this study, 42 breeding potato genotypes in Iran were selected based on appearance characteristics such as shape, size, color, eyes of tubers, and tuber yield and marketability. The tubers were evaluated for their nutritional value and properties, viz. phenolic content, flavonoids, carotenoids, vitamins, sugars, proteins, and antioxidant activity. Potato tubers with white flesh and colored skin had significantly higher levels of ascorbic acid and total sugar. The result showed that higher phenolic, flavonoid, carotenoid, protein concentration, and antioxidant activity were noted in yellow-fleshed. Burren (yellow-fleshed) tubers had more antioxidant capacity in comparison to genotypes and cultivars, which did not differ significantly with genotypes 58, 68, 67 (light yellow), 26, 22, and 12 (white). The highest correlation coefficients in antioxidant compounds were related to total phenol content and FRAP, suggesting that phenolics might be crucial predictors of antioxidant activities. The concentration of antioxidant compounds in the breeding genotypes was higher than in some commercial cultivars, and higher antioxidant compounds content and activity were detected in yellow-fleshed cultivars. Based on current results, understanding the relationship between antioxidant compounds and the antioxidant activity of potatoes could be very helpful in potato breeding projects.

Investigation of the cell structure and organelles during autolytic PCD of Antirrhinum majus "Legend White" petals.

One of the classes of the plant developmental programmed cell death (PCD) is vacuolar cell death or autolysis. The results of the transmission electron microscope (TEM) studies indicated that this type of PCD occurs during the petal senescence of Antirrhinum majus "Legend White" flowers. The major hallmarks of the process related to the ultrastructure of the cells involved chloroplast degradation, vacuolation, chromatin condensation, cell wall swelling, degradation of Golgi apparatus, protoplasmic shrinkage, degradation of the endoplasmic reticulum, nuclear fragmentation, rupture of tonoplast, and plasma membrane. Macroautophagy and microautophagy processes were also clearly observed during vacuole formation. As in yeasts, in the present study, Golgi apparatus became autophagosome-like structures during degradation that had autophagy activity and then disappeared. Our results revealed a type of selective microautophagy, piecemeal microautophagy of the nucleus (PMN), in nuclear degradation during PCD of petals that has not previously been reported in plants. Moreover, vesicular structures, such as paramural and multilamellar bodies, were observed in some stages.

Ameliorative effects of ascorbic acid on tolerance to drought stress on pepper (Capsicum annuum L) plants.

Drought stress is an important environmental stress that clearly affect biological systems of plants. There is a possibility that growth regulators are able to protect plants under drought conditions. Ascorbic acid (AsA) plays a particular role on growth of plants and protects cells from oxidative damage caused by environmental stresses. This study emphasized the impacts of AsA on improving the drought tolerance of the pepper plants. Based on a factorial arrangement in a completely randomized design, the experiment had two factors. The first factor was drought: irrigation within the field capacity, moderate stress (irrigation within the 60% field capacity) and severe stress (irrigation within the 30% field capacity). The second factor was AsA: 0 mM sprayed with distilled water, 0.5 mM and 1 mM. The experiment had three replications. Drought stress inhibited plant growth parameters including fruit number, height, weight, yield, chlorophyll a and b, total chlorophyll, carotenoid contents, it caused improvement in activity of catalase (CAT), peroxidase (POD), superoxide dismutase (SOD), proline content, anthocyanins, soluble sugars, malondialdehyde (MDA) and H2O2 in the leaves of sweet pepper. Application of AsA contributes to an increase in antioxidant enzymes activity such as SOD, CAT, POD and proline contents, chlorophyll a and b, total chlorophyll, carotenoids, soluble carbohydrates. However, it reduced the content of anthocyanins, MDA and H2O2. Based on this study, it can be suggested that ascorbic acid adjusted antioxidant activity, especially after it has been subjected to drought stress.